The present invention is directed to an improvement in a protection tube arrangement for a glass fiber, which tube is particularly useful for positioning a fiber in a housing of an opto-electronic module with a tip of the fiber adjacent a component of the module. The tube arrangement includes a glass fiber being positioned in a stiff protection tube with the tube surrounding and protecting the fiber and aligning the fiber with the component. The tube is composed of a metal having a poor thermal conduction and the module has a temperature range for a storage period which is a non-operation and for an operation period, which range is between a maximum or upper temperature limit and a minimum or lower temperature limit.
An arrangement, wherein a fiber is positioned in a tube which projects into a module to position the tip of the fiber to a component is disclosed in U.S. patent application Ser. No. 659,892, filed Oct. 11, 1984, which U.S. application claims priority from German Application No. P 33 37 131.8. It is noted that this application is silent about the thermal conductivity of the protection tube.
The present invention has been specifically developed for an opto-electronic transmission module or, respectively, reception module, of a telecommunications system. Over and above this, however, it is also suited for all opto-electronic modules which are supplied with light signals via a glass fiber or which produce an output light signal which is to be coupled into a glass fiber.
It has been shown that a glass fiber in a protective tube even after it has been secured in a protective tube must be protected against fracture, for example, from excessive longitudinal tensile stresses in the glass fibers and from severe impact load on the protective tube. In addition, because the taper on the end of the glass fiber is usually projected rigidly out of the first tube end of the protective tube only slightly and must be aligned to the optical active location of the opto-electronic component, which is inside of the module housing with a precision that is often extreme, for example, exactly 0.1 .mu.m, problems with movement of the fiber or tube do occur. For example, care must be taken that the securing of the fiber in the protective tube does not cause a deforming or movement of the fiber because of creep due to a continuous longitudinal tensile stress of the type which would cause the taper to be slowly moved out of the desired position. Thus, a long-time stability of the fiber in the tube is desirable and required.
It has been particularly shown that such dangers for glass fibers and/or their fastenings and for the taper adjustments, are produced not only because of blows but also because of temperature changes. This is because given an increase in the temperature, the protective tube normally expands more than the glass fiber which is suspended between two fastening locations on the tube. This causes excessive tensile stresses to be applied on the fiber.